1. Field
This invention relates generally to the field of peripheral computer input devices, and more particularly to a computer mouse of the type which controls cursor movement on a video display and the various “click” controls, which implement the “select” function, the “drag” function, the “scroll” function, the “page” function, and so forth.
2. Description of the Related Art
A mouse is used as a computer input device to control the location of a cursor on a video display connected to the computer. Typically, cursor location is controlled by movement of the mouse across a surface. The mouse includes a tracking device for measuring the movement of the mouse across the surface. This movement is relayed to the computer where it is translated into a corresponding movement of the cursor on the display. Several different tracking devices are known and used.
In addition, there are typically two or three buttons on the mouse for controlling switching functions. These switching functions are typically used to activate a function or command identified by the cursor location, or they can be set to control certain software features, such as highlighting in a word processor. Other mouse buttons may also be included and used to provide control for other software features such as scrolling or paging.
Many attempts have been made to design an easy to use computer mouse, which is ergonomically synchronized with the human form. Those attempts have generally been unsuccessful because the human hand comes in many shapes and sizes. Therefore, one size of computer mouse certainly does not fit all hand sizes. The result has been increasing incidents of carpal tunnel syndrome amongst mouse users as they struggle to conform their hands to the currently available designs.
The first computer mouse (the Engelbart mouse) was designed by a group of 17 researchers headed by Douglas C. Engelbart at the Stanford Research Institute in 1968. The Engelbart mouse was a handheld mobile device that used a combination of hardware and software to translate physical movements of a tracking device across a flat horizontal surface into digital signals to control movement of a cursor on a video display. Engelbart's design caused the user to orient his hand in a palm down posture on top of the mouse, with the hand and wrist arched upwardly. This hand posture proved to be the most popular amongst test groups and was the first to set the industry standard for the commercial computer mouse. The Engelbart design is used as the platform for all top selling computer mice and is the basis for many of the so-called “ergonomic” mouse product lines. Despite its commercial success, however, the Engelbart design places the user's hand and wrist in a “strained posture” (see FIG. 20). This posture causes excessive pressure on the hand, arm, and carpal tunnel of the wrist, and with repeated or prolonged use can result in repetitive stress injuries (“RSI”).
Repetitive stress injuries are a group of injuries occurring from a series of small repeated traumas. By themselves, none of these injuries causes permanent damage. However, when these movements are repeated hundreds or thousands of times, such as with standard mouse or keyboard movements, they often place unnecessary stress on the tendons and nerves of the hand, wrist, arm, shoulder, and neck resulting in debilitating pain, and loss of sensation. Carpal Tunnel Syndrome (“CTS”) is the most common RSI afflicting computer users today. CTS results from the pinching of the median nerve within the carpal tunnel of the hand, causing discomfort and numbness. The carpal tunnel is an opening into the hand that is made up of the bones of the wrist on the bottom and the transverse carpal ligament on top. Through this opening, the median nerve and the flexor tendons pass through into the hand. When abnormal pressure is placed on this area of the wrist, such as is caused by a conventional ergonomic mouse, this area can swell, pinching the nerve.
The problem with the standard Engelbart mouse design is that it requires a user to orient his hand in an unnatural upwardly arched posture known as the strained hand posture (see FIG. 20). In the strained hand posture, the weight of the user is not dispersed, but is concentrated on a small area located around the carpal tunnel of the wrist. As noted above, this can result in a pinching of the median nerve within the carpal tunnel causing discomfort and numbness. Moreover, if the user tenses his muscles at 20% of maximum, blood flow to the area is reduced by 80%. Most of today's commercially successful “ergonomic mice” are based on this design and thereby cause unnatural strain during use. It is this strain coupled with prolonged use that often results in the development of debilitating RSIs.
It would therefore be advantageous to design a computer mouse that required the user to keep her hand and wrist in a neutral hand posture during use, which is the posture that places the least amount of stress on the muscles and tissues of the hand, wrist, arm, and neck. In this neutral hand posture, the user's hand and wrist remain in a flatter, unarched posture, and the individual's weight is evenly dispersed between the hand, wrist, and arm. This posture minimizes the pinching of the median nerve within the carpal tunnel and allows for the greatest amount of blood flow to and from the hand by limiting the amount of flexion, extension and ulnar and radial deviation of the hand and wrist.
In addition to hand and arm strain, one major disadvantage of the conventional mouse design is that users often must spend valuable time searching their desktops to locate the mouse before using it. This disrupts the creative process and hinders both user performance and productivity.
Some attempts have been made to solve these problems by locating a tracking device, such as a track ball or a sensor pad, right on the computer keyboard, but some find these devices awkward to use and difficult to master. Moreover, such devices still require the user to remove his or her eyes from the display to find the exact location of the tracking device. This process can interrupt work flow and reduce productivity.
One solution to these problems is to integrate the functions of a computer mouse with the individual user's hand. A recent attempt to do this is described in U.S. Pat. Nos. 5,444,462, and 6,097,369 issued to Wambach on Aug. 22, 1995 and Aug. 1, 2000, respectively. Wambach describes a glove to be worn on a user's hand wherein the glove includes micro-switches mounted next to a joint of the index finger and on opposite sides of the wrist. The switches translate up and down movement of the index finger and side to side movement of the wrist into vertical and horizontal movements, respectively, of a cursor on a computer display. Buttons are provided on the other fingers to provide mouse clicking functions and to turn the glove on and off. These buttons are activated by the thumb. Although the device described by Wambach does not require a surface over which a tracking device must be moved, it does require a great deal of skill and considerable practice for the user to be able to control a cursor on a video display with any degree of accuracy. Further, the device must be manually activated prior to use and manually deactivated after use so that hand movements are not inadvertently translated into cursor movements on the screen while the user is typing. Moreover, Wambach's design restricts movement of the hand during operation to small movements of the wrist (side to side), index finger (up and down), and thumb (activating click buttons). This results in reduced blood flow to the hand when compared to other mouse designs which require whole arm movements.
Another recent attempt at a solution is described in U.S. Pat. No. 6,154,199 issued to Butler on Nov. 28, 2000. Butler describes a hand positioned mouse which includes a glove having a tracking ball supported in a housing attached to the side of the index finger so that the tracking ball can be operated by the thumb. Mouse buttons are positioned on the palm of the glove for activating mouse “click” functions. Transmission means are contemplated for sending signals corresponding to tracking ball movement to the computer. However, Butler makes no provision for using a tracking device that includes an optical sensor or for using a tracking device in contact with a surface. Moreover, Butler's tracking device and mouse “click” buttons do not automatically turn “off” when not in use to permit typing, and do not automatically turn “on” again when required for moving the cursor and performing mouse “clicking” functions. Butler's device also does not include “scrolling” or “paging” functions. Further, Butler's design restricts movement of the hand during operation to small movements of the thumb and fingers required to activate the tracking device the mouse click buttons. This results in reduced blood flow to the hand when compared to other mouse designs which require whole arm movements.
From the above, it is clear that there is a need for a more ergonomically efficient mouse design to reduce or prevent injury and to improve productivity and performance.